Left Ventricular Longitudinal and Circumferential Layer-Specific Myocardial Strains and Their Determinants in Healthy Subjects.

Abstract

The reference values and impact of physiologic variables on echocardiographic quantification of left ventricular (LV) longitudinal and circumferential layer-specific myocardial strains in large series of healthy persons remain unknown. This study prospectively investigated the impact of age, gender, and other physiologic parameters on LV longitudinal and circumferential layer-specific myocardial strains. 119 healthy volunteers (age range, 22-76; 50% women) underwent echocardiography. Short-axis (for circumferential strain) and apical (for longitudinal strain) views were analyzed using modified speckle tracking software enabling the analysis of strains in three myocardial layers. In normal subjects, longitudinal and circumferential strain was highest in the endocardium and lowest in the epicardium, longitudinal and circumferential three-layer strain was highest in the apex and lowest in the base. The mean global longitudinal strain in the endocardial layer (GLS-endo), in the mid-myocardial layer (GLS-mid) and in the epicardial layer (GLS-epi) were -24.3 ± 3.1%, -21.3 ± 2.9%, and -18.9 ± 2.8%, respectively. Gender, HR, and SV (stroke volume) were independent predictors of GLS-endo, GLS-mid, and GLS-epi. The mean global circumferential strain in the endocardial layer (GCS-endo), in the mid-myocardial layer (GCS-mid) and in the epicardial layer (GCS-epi) were -34.3 ± 4.4%, -20.5 ± 3.0%, and -11.8 ± 2.7%, respectively. HR independently predicted GCS-endo, GCS-mid, and GCS-epi. Three-layer analysis of longitudinal and circumferential strain using two-dimensional speckle tracking imaging (2DSTI) can be performed on a clinical basis and may become an important method for the assessment of real time, quantitative global, and regional LV function.